1. Field of the Invention
The present invention relates to a liquid crystal display (LCD), and more specifically, to a heat shielding film for preventing deformation of a reflecting plate and characteristic degeneration of liquid crystal due to heat generated from an inverter for driving a lamp that emits light necessary for a displaying operation and thus preventing partial or entire degeneration of displaying performance, and an LCD using the same.
2. Description of the Related Art
Generally, an LCD is defined as one of a flat panel display for displaying a desired character, image and moving picture using a physical and optical characteristic of liquid crystal.
The LCD performs a displaying operation in a digital control method—in contrast with a conventional CRT (cathode ray tube) type display that performs the displaying operation in an analog control method. This offers an advantage of less weight and volume than the CRT type display even though the LCD has the same resolution and displaying surface area as the CRT.
However, in the LCD, the liquid crystal that plays a conclusive role in performing the displaying operation cannot emit light by itself. Therefore, the LCD has a disadvantage in that it is impossible to perform the displaying operation unless the light is externally supplied, even through the liquid crystal is precisely controlled.
In the LCD, natural light or artificial light generated by consuming electric energy charged therein is primarily used as the light that is essential for performing the displaying operation.
Currently, the LCD using natural light has a fatal defect in that It is impossible to perform the displaying operation in a location that does not have enough natural light. Therefore, recently, the LCD using the artificial light generated by consuming the electric energy has been actively developed and used.
A CCFL (cold cathode fluorescent lamp) type lamp is mainly used as a light source for the LCD that uses artificial light. The CCFL type lamp generates white light that is close to natural light, and generates less heat and provides a longer life span. Although the CCFL type lamp has these advantages, however, since the lamp requires a very high driving voltage, it Is impossible to drive the lamp with only the low voltage used for controlling the liquid crystal of the LCD.
Therefore, the LCD needs an inverter including an IC device and a transformer for boosting a lower voltage to a high voltage that is required to drive the CCFL type lamp. Since the inverter is generally formed on a printed circuit board, it is impossible to dispose the inverter at a side portion of the thin LCD. Therefore, the inverter is generally disposed at a rear face of the LCD adjacent to the CCFL type lamp.
However, when the inverter is disposed at the rear face of the LCD, as described above, the display quality degrades seriously at a screen portion of the LCD corresponding to the inverter. The problem is caused by an operating characteristic of the inverter.
In concrete terms, the transformer as a core portion of the inverter generates excessive heat during the boosting operation, and the IC device also generates excessive heat during a data processing operation. The heat generated from the inverter is transferred to a reflector panel. The LCD is contained in a receiving container and the heat directly influence the reflector panel Also, the heat indirectly generates a humming in a light guiding plate and an optical sheet stacked on an upper face of the reflector panel, further influencing the liquid crystal of an LCD panel assembly.
Currently, the receiving container is formed with an opening at a bottom face thereof within an area that does not influence the strength thereof to reduce the weight of the LCD. The heat generated from the inverter, both directly and locally, heats the reflector panel through the opening.
If a portion of the reflector panel is locally heated, thermal expansion of the heated portion of the reflector panel is greater than that of a non-heated portion of the reflector panel. Therefore, the reflector panel is extended, and a surface of the reflector panel is thus expanded.
If the surface of the reflector panel is expanded as described above, a reflecting characteristic of the expanded portion of the reflector panel is different from that of a remaining portion of the reflector panel. As the result, as shown in FIG. 1, a dark space 1 is generated on a screen 10 opposite to the inverter (not shown).
If the heat generated from the inverter is exerted for an extended time on the reflector panel, the Light guiding plate, optical sheets and LCD panel assembly, another problem arises, that is, lowering the optical characteristic according to the local expansion of the light guiding plate, the optical sheets as well as the reflector panel.
Moreover, in the case where the heat generated from the inverter module heats the liquid crystal of the LCD panel assembly, the liquid crystal (having a middle characteristic between a liquid medium and a solid medium) has a characteristic inclined to the liquid medium. Therefore, another critical problem develops in that an inherent function of the liquid crystal is lost, so that the displaying operation can no longer be performed.
The problems generated at the inverter as described above became more serious since a displaying surface area of the LCD has been increased recently. This is caused because the wider the displaying surface area is the longer the lamp becomes, and also a driving voltage of the lamp is increased according to an increase in the length of the lamp, thereby generating more heat at the inverter,
Therefore, in order to realize a large-sized LCD, it is required that the heat generated from the inverter does not exert an influence on all constructing elements of the LCD.